It's a a propellantless microwave thruster that defies Newton's laws of motion

Chinese scientists have taken on a heavily criticized space drive idea that could one day launch satellites, deep space probes and even flying cars.

The research team hails from Northwestern Polytechnic University in Xi'an, and was led by Yang Juan. What they developed was a propellantless microwave thruster called EmDrive, which is a controversial idea because it goes against Newton's laws of motion -- and many have claimed to create a "propellantless" thruster before and failed.

Newton's laws of motion are all based on the idea that firing propellant out of the back at a high speed will push a craft forward. While solar cells offer infinite power, thrust is limited by propellant. Many have tried to get around this, but several scams have made this particular field a joke in the scientific world.

While space drives tend to rely on Newton's laws of motion, the EmDrive is a closed, conical container that has a net thrust toward the wide end when filled with resonating microwaves. This goes against Newton, who said that no closed system could have a net thrust. However, EmDrive works because the microwaves have a group velocity (the speed of a collection of electromagnetic waves) that is greater in one direction than the other -- which is where Albert Einstein's theory of relativity comes in.

British engineer Robert Shaywer, who began looking at the concept of a propellantless thruster when he opened his own company called Satellite Propulsion Research in 2001, is the original creator of the EmDrive. He made demonstration thrusters to prove it could be done, and even made sure the test results were accurate (meaning, the results weren't affected by friction, ionization, air currents, electromagnetic effects or interference). The first, made in 2003, had a thrust of 16 mN. This was enough to show it could be done.

However, he received a ton of criticism for his idea and was ridiculed in his own country. But the Chinese team at Northwestern Polytechnic University believed in his research and took the project head on to author the latest study, "Net Thrust Measurement of Propellantless Microwave Thruster."

The Northwestern Polytechnic University team was able to create the EmDrive with 720 mN of thrust with a couple of kilowatts of power.

So what purpose does EmDrive have? It could halve launch costs of satellites because as much as half the launch weight of these objects are attributed to propellant.

Shawyer is even working on a superconducting thruster that could be ready as soon as 2016. It would boost the Q value of the cavity, which determines the amount of thrust produced. He said it could be boosted by a factor of several thousand, possibly equating to a tonne of thrust per kilowatt of power.

quote: If we had accepted that rules could not be broken then no cars would be travelling at over 30mph, as that was the speed where everyone was told people would not be able to breath. yes crazy but it was a real Law that they said could not or should not be broken.

Name one -- just ONE -- legitimate scientist who supported this BS. The scientific community knew this was not true. Hell, anyone who had seen a cheetah run or seen a swallow dive knew that 30 mph was no kind of speed limit!

People confuse laws with scientific theories. And too many of the general public confuse "common wisdom" with scientific theory. They are three very, very different things.

"Common wisdom" is very, very often wrong. Some refer to them as "myths", and there is even a TV show out to bust most of these myths.

Scientific theory is sometimes wrong, but more often than not it just gets modified or tweaked when new, verified -- and independently reproducible -- data shows up.

Laws are never wrong. Laws are simply a statement of fact -- a statement of the data that has been recorded time and time and time and time again. There is the "Law of Gravity". Things fall toward each other. There is gravitational attraction. The theory is that it follows a simple inverse square relationship based upon some universal, measurable constant and the mass of the two bodies. That's the theory anyway. There have been some experiments in the last 30 years that may give an indication that the relationship is not a simple inverse square law, but the effect is so subtle that no one has been able to reproduce it with enough fidelity that the theory can justifiably be modified. The common wisdom is that different items are affected by gravity differently which is utter BS.

quote: I suspect that if we had to ignore all the supposed laws we would be moving much faster in development of new technologies.

Now you sound like my crazy "inventor" friend who told me many, many years ago, "I'm not a physicist like you. I'm not bound by any of your laws." Yea, right. How's that jumping off a 1,000 foot cliff working for you?

quote: Laws are never wrong. Laws are simply a statement of fact -- a statement of the data that has been recorded time and time and time and time again.

If you break a law, you go on trial. If you break a "law of nature", the law goes on trial.

As you correctly pointed out, laws are basically our tenants on how things work. Relativity was an example that violated traditional Newtonian physics, but our definition of the law was modified to account for it. The fundamental physics never change, but our understanding of the laws do.

As for this topic, I have no idea why this article is portraying this as some revolutionary or controversial advancement.

First off, it is not a closed system as it requires external energy to operate.

Secondly, the idea of propulsion from the emission of electromagnetic radiation is well documented. That is the basis for the solar sail. While photons do not have any mass, they do have impulse energy that can be transferred.

Thirdly, the speculation in that article that this work could provide launch capabilities is laughable.

quote: Thirdly, the speculation in that article that this work could provide launch capabilities is laughable.

While we are well advised to use words like "never" rather sparingly, in this case I agree with you that the promise of propulsion such as this (assuming it turns out to be real and not a hoax) fall far short of launching spacecraft into orbit from the surface of the Earth. They are talking about thrust on the mN scale and even at the order of magnitude improvement projected, it would probably not be sufficient for any kind of launch.

That being said it could be useful for deep space probes, again if it works at all. The only launch I can imagine it being used for is departing from a halo orbit around a Lagrange point. It might have enough thrust to pull that off.

quote: As you correctly pointed out, laws are basically our tenants on how things work.

Not true. "How" things work is the theory.

Pick up a rock and release it. I falls. Pick it up again and release it again. It falls. Do that one billion times and the rock falls every time. That's the LAW of gravity. Laws are the simple, observed facts. They don't change. Our understanding of HOW it works can change. The HOW is the theory.

Now "how" gravity works, e.g., the inverse square relationship (note I did NOT say inverse square LAW) is a theory. As I mentioned there have been a few experiments in the last several years that have cast a tiny bit of doubt on gravity following an inverse square relationship. So the Theory *MIGHT* need to be tweaked. However, the LAW still holds.

Unfortunately, as I mentioned before, many, many people confuse Physical Laws with Theories about the Physical Laws. They are not the same. Not even close.

quote: Relativity was an example that violated traditional Newtonian physics, but our definition of the law was modified to account for it. The fundamental physics never change, but our understanding of the laws do.

No. Simply, No. The Law does not change. Newton's theory on how gravity works was flawed (mostly correct, but not quite). Einstein's theory of General Relativity modified Newton's theory. It did not change the law or modify our understanding of the law. Relativity modified the theory. It modified how we try to explain the law.

There is no such thing as a "Law" other than what we, as a human race, has determined to be a law.

The fundamental physics is the law, of which we only have a superficial understanding. We have then divided portions of that physics we think we understand into scientifically proven directives that we call "Laws". Your concept of a law as an observed phenomenon (eg drop rock billions of times) is incorrect and not supported by the scientific community. You can adopt your own bastardized definition of a "law" anyway you want, and then attempt to argue from that vantage point. I won't indulge you.

The quote I mentioned before about a scientific law going on trial if violated was from the late, great Carl Sagan. But I'm sure he had no idea what he was talking about.